The present invention relates to a new and improved apparatus and method for use in cushioning movement of a member in a press during operation of the press between open and closed conditions.
A piston and cylinder have previously been used in a cushion assembly to cushion movement of a member during operation of a press between open and closed conditions. In order to maximize the operating life of the cushion assembly, it is necessary to maintain seals between the piston and cylinder lubricated during operation of the cushion assembly. It has previously been suggested that th seals between the piston and cylinder in a press cushion assembly be lubricated in any one of many different ways, including those disclosed in U.S. Pat. Nos. 4,076,103; 4,688,775; 4,691,902 and 4,815,718.
Although known seal lubrication arrangements used in press cushion assemblies have been more or less successful, difficulty has been encountered in lubricating the seals in certain press cushion assemblies. For example, difficulty has been encountered in lubricating seals in press cushion assemblies having a relatively short stroke, that is a stroke of 0.50 inches or less, and operated at a relatively high rate, that is at a rate of 100 cycles per minute or more. Thus, it is desired to operate one known press at a rate of more than 100 cycles per minute around the clock, that is for twenty-four hours a day and seven days a week. The cushion assemblies in this known press have a stroke of less than 0.50 inches. When this particular press is operated in this manner, the cushion assemblies are replaced after a million cycles or approximately one week of use.
It is believed that a cushion assembly in the press described above fails as a result of a lack of lubrication of the seals between the piston and cylinder in the cushion assembly. Thus, the cushion assembly piston moves so rapidly and through such a short stroke that it is difficult to maintain the seals lubricated during use of the press.